The match lasted 47 minutes.
Marin on the other hand, has been struggling with her fitness since previous year and has been able to perform at her best ever since her Rio Olympics triumph.
This is Sindhu's first India Open win.
Everyone interested in this Carolina-Sindhu clash had the result of the Rio Olympic final in mind. But it's the Indian who won their last meeting on the global stage, having defeated Marin 21-17, 21-13 in the group stage of the season-ending World Superseries finals in Dubai previous year.
The two players have been involved in some brilliant clashes, including the Rio Olympics gold medal clash. While she dominated the back court, she was also beating Marin to the net.
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However, members of the family refused to condemn killer Masood or his actions as Clint Payne added: "There is no ill feeling". In a second picture, captioned "Getting stronger every day", she stands on crutches in her hospital gown smiling defiantly.
Gopichand, who shaped Sindhu and Olympic bronze-medallist Saina Nehwal among others, believes it will take some time for the next big star to emerge.
Just the start of April and this is Sindhu's second title of the season already, having bagged the China Open earlier this year.
In the 47-minute battle in front of packed stands at the Siri Fort Sports Complex, Sindhu came up with a series of unbelievable strokes from her armoury to leave the reigning World and Olympic champion completely stunned. After the interval, Hyun misjudged a shuttle at the baseline and struggled with the length as Sindhu led 13-10.
Marin did close the gap in the later stages and even took a 19-18 lead at one point, but Sindhu grabbed three straight points to pocket the first game. Psychologically, this proved a massive blow and dictated the course of the match.
Both players agreed that the closing points of the first game was the decisive phase of the match. But Sindhu held firm thereafter and won the game in 24 minutes. "That's the way it goes", said Sindhu. "We were not in the mood to give it away and played long rallies and eventually I came out on top", She said after the match. I could see she was getting good support from fans today. While, SIndhu, considering her recent form, will start the clash as favourite, Marin, with her never-say-die attitude, can be risky. But, today was an all-new day a whole new game.